swift UIColor使用Hex String创建

Posted 2021-05-19

extension UIColor {

    convenience init(hex: String) {
        let hexStr = hex.lowercased().replacingOccurrences(of: "0x", with: "")
        let hexmap = hexStr.map { String($0) }
            + Array(repeating: "0", count: max(6 - hexStr.count, 0))
            + Array(repeating: "f", count: max(8 - max(6, hexStr.count), 0))
        let split = stride(from: 0, to: hexmap.count, by: 2)
            .map { hexmap[$0..<$0+2]
                .reduce(into: String()) { $0 += $1 } }
        let hexRGB = split.map { CGFloat(Int($0, radix: 16) ?? 0) / 255.0 }
        self.init(red: hexRGB[0],
                  green: hexRGB[1],
                  blue: hexRGB[2],
                  alpha: hexRGB[3])
    }

}